In a flat knitting machine or circular knitting machine, a knitting member such as a needle is selected with a selection actuator, and the selected needle is driven with a carriage cam. A problem associated with the selection actuators is how to make them compatible with fine-gauge knitting machines. A gauge of a knitting machine represents a number of needles per 1 inch, and with a fine gauge, the knitting members have to be selected with a small pitch.
International patent application WO02/18690 describes that a non-magnetic body is inserted between a control magnetic pole (a magnetic pole for controlling the magnetization state in a coil and using it for selecting a knitting member) and a fixed magnetic pole (a magnetic pole that is magnetized in a fixed state, for example, with a permanent magnet), and a leakage magnetic flux from the fixed magnetic pole is prevented from penetrating into the control magnetic pole. This application also discloses that coils of control magnetic poles are used to bypass the gap between the fixed magnetic poles and to form a magnetic circuit from the permanent magnet via the fixed magnetic pole and coil to the fixed magnetic pole and permanent magnet on the opposite side. Japanese Patent No. 2878166 and European Patent No. EP0474195B disclose a configuration in which a plurality of control magnetic poles are provided in one selection unit, but they do not describe the control thereof.
Where a fine-gauge knitting machine is employed, the thickness of knitting members is also reduced and the time that can be used for selecting individual knitting members is shortened. As a result, the knitting members are difficult to select.